Scaling violations of quark and gluon jet fragmentation functions in e+ e- annihilations at s**(1/2) = 91.2-GeV and 183-GeV - 209-GeV.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 37 (2004) 25-47, 2004.
Inspire Record 648738 DOI 10.17182/hepdata.74689

Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of 91.2, and 183-209 GeV with the OPAL detector at LEP. The unbiased jets are defined by hemispheres of inclusive hadronic events, while the biased jet measurements are based on three-jet events selected with jet algorithms. Several methods are employed to extract the fragmentation functions over a wide range of scales. Possible biases are studied in the results are obtained. The fragmentation functions are compared to results from lower energy e+e- experiments and with earlier LEP measurements and are found to be consistent. Scaling violations are observed and are found to be stronger for the fragmentation functions of gluon jets than for those of quarks. The measured fragmentation functions are compared to three recent theoretical next-to-leading order calculations and to the predictions of three Monte Carlo event generators. While the Monte Carlo models are in good agreement with the data, the theoretical predictions fail to describe the full set of results, in particular the b and gluon jet measurements.

11 data tables

The udsc jet fragmentation function in bins of $x_{\rm E}$ and scale. The scale denotes $Q_{\rm jet}$ for the biased jets and is given by the intervals, while it denotes $\sqrt{s}/2$ for the unbiased jets and is given by the single values. These data are displayed in Fig.7.

The b jet fragmentation function in bins of $x_{\rm E}$ and scale. The scale denotes $Q_{\rm jet}$ for the biased jets and is given by the intervals, while it denotes $\sqrt{s}/2$ for the unbiased jets and is given by the single values. These data are displayed in Fig. 8. In the region 0.48 $<x_{\rm E}<$ 0.90 and $Q_{\rm jet}=$ 30-70 GeV, no measurement was possible due to low statistics.

The gluon jet fragmentation functions in bins of $x_{\rm E}$ and scale $Q_{\rm jet}$ obtained from the biased jets using the b-tag method (BT). These data are displayed in Fig. 9. In the region 0.48 $<x_{\rm E}<$ 0.90 and $Q_{\rm jet}=$ 30-42 GeV for the b-tag method, no measurement was possible due to low statistics.

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Experimental studies of unbiased gluon jets from e+ e- annihilations using the jet boost algorithm

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Phys.Rev.D 69 (2004) 032002, 2004.
Inspire Record 631361 DOI 10.17182/hepdata.74246

We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the energy evolution of the distributions, specifically the mean and first two non-trivial normalized factorial moments of the multiplicity distribution, and the fragmentation function. The theoretical results are found to be in global agreement with the data, although the factorial moments are not well described for jet energies below about 14 GeV.

5 data tables

The charged particle multiplicity distribution of gluon jets, $n_{\rm gluon}^{\rm ch.}$, for $E_{\rm g}^*$$\,=\,$5.25, 5.98 and 6.98 GeV. The data have been corrected for detector acceptance and resolution, for event selection, and for gluon jet impurity.

The charged particle multiplicity distribution of gluon jets, $n_{\rm gluon}^{\rm ch.}$, for $E_{\rm g}^*$$\,=\,$8.43 and 10.92 GeV. The data have been corrected for detector acceptance and resolution, for event selection, and for gluon jet impurity.

The charged particle multiplicity distribution of gluon jets, $n_{\rm gluon}^{\rm ch.}$, for $E_{\rm g}^*$$\,=\,$14.24 and 17.72 GeV. The data have been corrected for detector acceptance and resolution, for event selection, and for gluon jet impurity.

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Jet production in charged current deep inelastic e+ p scattering at HERA.

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Krakauer, D. ; et al.
Eur.Phys.J.C 31 (2003) 149-164, 2003.
Inspire Record 620434 DOI 10.17182/hepdata.46434

The production rates and substructure of jets have been studied in charged current deep inelastic e+p scattering for Q**2>200 GeV**2 with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb**-1. Inclusive jet cross sections are presented for jets with transverse energies E_T(jet) > 14 GeV and pseudorapidities in the range -1 < eta(jet) < 2. Dijet cross sections are presented for events with a jet having E_T(jet) > 14 GeV and a second jet having E_T(jet) > 5 GeV. Measurements of the mean subjet multiplicity, , of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations a re compared to the measurements. The value of alphas(M_Z), determined from at y_cut=0.01 for jets with 25

20 data tables

Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1995-1997 sample.

Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1999-2000 sample.

Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the combined sample.

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Measurement of deeply virtual Compton scattering at HERA.

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Krakauer, D. ; et al.
Phys.Lett.B 573 (2003) 46-62, 2003.
Inspire Record 618776 DOI 10.17182/hepdata.46432

The cross section for deeply virtual Compton scattering in the reaction ep -> e gamma p has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb-1 of e+p and 16.7 pb-1 of e-p collisions. Differential cross sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the gamma*p system in the region 5 < Q2 < 100 GeV2 and 40 < W < 140 GeV. The measured cross sections rise steeply with increasing W. The measurements are compared to QCD-based calculations.

4 data tables

Measurements of the DVCS process cross section as a function of Q**2 at average W = 89 GeV. Data are given seperately for the E+ P and E- P interactions.

Measurements of the DVCS process cross section as a function of W at average Q**2 = 9.6 GeV**2. For the E+ P data sample.

Measurements of the DVCS process cross section as a function of W at average Q**2 = 9.6 GeV**2. For the E- P data sample.

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Measurements of inelastic J/psi and psi' photoproduction at HERA.

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.
Eur.Phys.J.C 27 (2003) 173-188, 2003.
Inspire Record 601166 DOI 10.17182/hepdata.46546

The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 38.0 pb-1. The events were required to have 0.1 < z < 0.9 and 50 < W < 180 GeV, where z is the fraction of the incident photon energy carried by the J/psi in the proton rest frame and W is the photon-proton centre-of-mass energy. The psi' to J/psi cross-section ratio was measured in the range 0.55 < z < 0.9. The J/psi data, for various ranges of transverse momentum, are compared to theoretical models incorporating colour-singlet and colour-octet matrix elements. Predictions of a next-to-leading-order colour-singlet model give a good description of the data, although there is a large normalisation uncertainty. The J/psi helicity distribution for z > 0.4 is compared to leading-order QCD predictions.

10 data tables

Measurment of the total cross section, with various PT thresholds, in the high Z > 0.9 region.

Ratio of cross section for PSI(2S) to J/PSI production. as a function of PT. Statistical errors only.

Ratio of cross section for PSI(2S) to J/PSI production. as a function of W. Statistical errors only.

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Inclusive jet cross sections in the Breit frame in neutral current deep inelastic scattering at HERA and determination of alpha(s).

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 547 (2002) 164-180, 2002.
Inspire Record 593409 DOI 10.17182/hepdata.46572

Inclusive jet differential cross sections have been measured in neutral current deep inelastic e+p scattering for boson virtualities Q**2>125 GeV**2. The data were taken using the ZEUS detector at HERA and correspond to an integrated luminosity of 38.6 pb-1. Jets were identified in the Breit frame using the longitudinally invariant K_T cluster algorithm. Measurements of differential inclusive jet cross sections are presented as functions of jet transverse energy (E_T,jet), jet pseudorapidity and Q**2, for jets with E_T,jet>8 GeV. Next-to-leading-order QCD calculations agree well with the measurements both at high Q**2 and high E_T,jet. The value of alpha_s(M_Z), determined from an analysis of dsigma/dQ**2 for Q**2>500 GeV**2, is alpha_s(M_Z) = 0.1212 +/- 0.0017 (stat.) +0.0023 / -0.0031 (syst.) +0.0028 / -0.0027 (th.).

9 data tables

Inclusive jet cross section DSIG/DQ**2 for jets of hadrons in the Breit frame.

Inclusive jet cross section DSIG/DET for jets of hadrons in the Breit frame.

Inclusive jet cross section DSIG/DETARAP for jets of hadrons in the Breit frame.

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Inclusive analysis of the b quark fragmentation function in Z decays at LEP. ((B))

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 29 (2003) 463-478, 2003.
Inspire Record 599181 DOI 10.17182/hepdata.43196

A study of b quark hadronisation is presented using inclusively reconstructed B hadrons in about four million hadronic Z decays recorded in 1992-2000 with the OPAL detector at LEP. The data are compared to different theoretical models, and fragmentation function parameters of these models are fitted. The average scaled energy of weakly decaying B hadrons is determined to be <xe>=0.7193+-0.0016(stat)+0.0036-0.0031(syst)

4 data tables

No description provided.

Correlation matrix of statistical uncertainties.

Correlation matrix of positive systematic uncertainties.

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Measurement of proton dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERA.

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.
Eur.Phys.J.C 26 (2003) 389-409, 2003.
Inspire Record 587202 DOI 10.17182/hepdata.46584

Diffractive photoproduction of vector mesons, gamma p --> V Y, where Y is a proton-dissociative system, has been measured in ep interactions with the ZEUS detector at HERA using an integrated luminosity of 25 pb^-1. The differential cross section, ds/dt, is presented for -t<12 GeV^2, where t is the square of the four-momentum transferred to the vector meson. The data span the range in photon-proton centre-of-mass energy, W, from 80 GeV to 120 GeV. The t distributions are well fit by a power law, ds/dt ~ (-t)^{-n}. The slope of the Pomeron trajectory, measured from the W dependence of the rho^0 and phi cross sections in bins of t, is consistent with zero. The ratios ds_(gamma p --> phi Y)/dt to ds_(gamma p --> rho^0 Y)/dt and ds_(gamma p --> J/psi Y)/dt to ds_(gamma p --> rho^0 Y)/dt increase with increasing -t. Decay-angle analyses for rho^0, phi and J/psi mesons have been carried out. For the rho^0 and phi mesons, contributions from single and double helicity flip are observed. The results are compared to expectations of theoretical models.

8 data tables

Differential cross section for RHO0 production. The second DSYS error is due to the modelling of the proton-dissociation process.

Differential cross section for PHI production. The second DSYS error is due to the modelling of the proton-dissociation process.

Differential cross section for J/PSI production. The second DSYS error is due to the modelling of the proton-dissociation process.

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Measurement of the Q**2 and energy dependence of diffractive interactions at HERA.

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.
Eur.Phys.J.C 25 (2002) 169-187, 2002.
Inspire Record 584714 DOI 10.17182/hepdata.46612

Diffractive dissociation of virtual photons, gamma* p-->Xp, has been studied in ep interactions with the ZEUS detector at HERA using an integrated luminosity of approx. 10 pb^-1. The data cover photon virtualities 0.17 < Q^2< 0.70 GeV^2 and 3 < Q^2< 80 GeV^2 with 3

9 data tables

The double differential cross section d2sig/dmx/dt measured with the LPS method for the Q**2 range 0.17 to 0.70 GeV**2.

The double differential cross section d2sig/dmx/dt measured with the LPS method for the Q**2 range 3 to 9 GeV**2.

The double differential cross section d2sig/dmx/dt measured with the LPS method for the Q**2 range 9 to 80 GeV**2.

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Exclusive photoproduction of J/psi mesons at HERA.

The ZEUS collaboration Chekanov, S. ; Krakauer, D. ; Magill, S. ; et al.
Eur.Phys.J.C 24 (2002) 345-360, 2002.
Inspire Record 582237 DOI 10.17182/hepdata.46713

The exclusive photoproduction of J/psi mesons, gamma p->J/psi p, has been studied in ep collisions with the ZEUS detector at HERA, in the kinematic range 20

12 data tables

The total exclusive J/PSI photoproduction cross section, the differential cross section extrapolated to t=0 and the slope parameter of the exponential t dependence as afunction of W, the photon-proton c.m. energy, for data from J/PSI muon decay.

The total exclusive J/PSI photoproduction cross section as a function of W,the photon-proton c.m. energy, for data from J/PSI electron decays.

The differential cross section extrapolated to t=0 and the slope parameter of the exponential t dependence for exclusive J/PSI photoproduction as a function of W, the photon-proton c.m. energy for data from J/PSI electron decays.

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